圆管有很多直径的呀,最小的有医疗用的那种和针一样,当然还有别的常规的有9.5,15.9,19.1,25.4,31.8,38.1,大的还有88.9,101.6,114,141,168,159,219,273,323,
406,.630当然还有更大的